Electron emitter



July 2, 1929. H. T. REvE' ELECTRON. EMITTER Filed Aug. 26, 1924 ff Ulf/df" effe,

Panama July 2., 1929.

` UNITED STATES PATENT'OF Freak HOWARD T. REEVE, OF MILLBURN, NEW JERSEY, ASSIGNOR TO vVTESTEB'N ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEWYORK-- ELIECTRON EMITTER.

Application filed This'invention relates to electron discharge devices and has for its object an electron emitter and process of making the same. l

Most materials of high thermionic activlty cannot be made in filament form. It has therefore been the usual practice to coatthermionically active material on a filament having suitable physical and electrical character- `istics. The product thus obtained is apt to lack uniformity. This invention contemplates incorporating the thermionically -active material in the metal of the filament to secure a uniform'homogeneous product.

Referring now to the drawings, theyarious figures thereof are illustrative of the steps in the process of producing an electron emitter according to this invention.

Fig. 1 1s a sectional view of a metal receptacle containing the desired molecular portions of barium and strontium carbonates` and atomic portions of nickel being heated to form nickelites of barium and strontium.;

Figs. 2 and 3V are sectional views of a suitable die andblock to press the powdered nickelite into a rodi;

Fig. 4 is a sectional view of avacuum furnace to break down the nickelites toyield the oxides of the earth metals;

Fig. 5 shows a suitable swaging machine to form the rod into wire;

swaging dies shownin Fig. 5; and Fig. 7 is a sectional view of one of the suc cession of dies through which the wire is passed to reduce it to the vacuum tube filaments. l

A filament made in accordance with this invention may comprise a high melting point alloy such as platinum-nickel or a metal such as tungsten throughout which is uniformly distributed oxides of the alkaline earth metals. The process of manufacture will be described in detail in connection with a platinum-nickel filament having strontium and barium .oxides 45 incorporated therein.

Y Proper molecular portions of the carbonates of barium and strontium and atomic portions of nickel are mixed in a metal boat 10 and heated by means of Oxy-hydrogen flames 11 or the liketo about 1200 degrees C. in the presaugust 2e, '1924. lsemaine. 734,217.

ence. of air or oxygen. Compounds of barium fand strontium with nickel and atmospheric .oxygen are formed which might be expressed BaO2 (N iO2) and conveniently termed nickelites of barium and strontium.

The product of this operation is crushed t0 a powder and mixed with a proper proportion of platinum powder. It is .thenv placed in a die 12 and by means of the block 13 is pressed into the form of a rod 14 as shown in Figs. 2 60 and 3.' The rod 14 is then placed in a vacuum furnace 15 of any of the well known types and is heated to a temperature of approximately 1600 degrees C. This heating in vacuum breaks down the nickelites yielding the oxides 65,v of the alkaline earth metals which are incorporated in and uniformly distributed throughout the platinum-nickel rod.

The rod 14 is then hammered down by swaging machine 16 until it is formed into a homo- 70 l ters having other constituents than those re- Fig. 6 is an enlarged view of one of the.

cited in connection with the detailed description of the process without in any way departing from the spirit of the invention as set forth in the appended claims. proper size for use as v .What is claimed is 8 1. The process of forming a cathode which comprises forming nickelites of alkaline earth metal, combining said nickelites with powdchred refractory metal to form a core, reducing said nickelites and working the product into 'lilamentary form.

2. The process of forming a cathode which comprises forming barium and strontium nickelites, combining said nickelites with platinum powder to form a core, heating said core lto reduce said nickelites and working the resulting product intofilamentary form.

Inwitness whereof, Ihereunto subscribe my name this 22nd .day of August A. D., 1924.

HOWARD T. REEVE. 

